The term “cocktail party effect” refers to a person's hearing ability to selectively focus on a particular voice while “filtering out” other voices, even in a normally noisy cocktail party. This is the result of a normal person's auditory system being able to “localize” a sound source and extract sound information from the location of the sound source. That is, even in a noisy environment, one may be able to have a conversation with a target speaker by simply focusing on him/her.
However, people with hearing impairment may not have the ability to localize the sound source. This is due to a “threshold of hearing” of a person with impaired hearing ability being higher than that of a normal person. In addition, people with only one normal ear may not have such an ability as well.
Conventional hearing aid systems are provided for helping a person with impaired hearing ability to localize a sound source. For example, a conventional hearing aid system may be configured to extract sound information from a front direction of a user, and process the extracted sound information to increase a signal-to-noise ratio (SNR). As a result, the user is able to listen clearly to the voice of a speaker in front of him/her even in a noisy environment.
Nonetheless, in cases where multiple people are present in front of the user, the conventional hearing aid system is unable to specify which one is (or ones are) the user's target speaker.